In ink-jet recording, an ink cartridge containing an ink is used. There is a case in which the ink cartridge is provided with a remaining ink detecting portion detecting the amount of remaining ink. The remaining ink detecting portion detects the amount of remaining ink on the basis of whether or not light is transmitted therethrough. On the other hand, there is a case in which a water-based ink of higher penetration (wettability) relative to a recording medium is used for the purpose of improving the quality of a recorded image in ink-jet recording. However, when the water-based ink of higher penetration is contained in an ink cartridge, even in the case where light should be transmitted through the remaining ink detecting portion with the decrease of water-based ink, there is the possibility that the water-based ink remains in the remaining ink detecting portion and inhibits the light transmission. This may cause a detection error. In order to solve the problem, it has been proposed to form a water-repellent membrane (ink-repellent membrane) on the remaining ink detecting portion of the ink cartridge by applying polyorganosiloxane.
However, in the aforementioned method, there is the possibility that the water-repellent membrane comes off over time, for example, and the prevention of the error in the detection of remaining ink is insufficient. Further, in the method, there is also the problem that the water-based ink may be contaminated with the water-repellent membrane that came off.